Conventionally, there is well-known a pneumatic tire for icy and snowy roads having a directional tread pattern including V-shaped grooves disposed therein, in which a center rib is provided on the equatorial plane of the tire in the tread surface to enhance ice performance (see Unexamined Japanese Patent Application Publication No. 2000-255217, for example). Since the center rib increases the ground contact area, ground contact properties with respect to icy road surfaces increase to enhance performance on ice.
However, Provision of the center rib reduces the ratio of groove area, compared with blocks, whereby a decrease in braking performance on wet road surfaces can not be avoided. Another problem is that snow traction performance is deteriorated.